San Francisco, California is an urban metropolis on the West Coast of the United States. Its 46.7 square miles (2.1) is home to approximately 8.15 million people (2) and is bordered on three sides by the Pacific Ocean and the San Francisco Bay. A couple of years ago San Francisco launched ten different programs run by SF Environment, the city’s Environmental Department, to improve its environmental impact and become a more sustainably city. One of these programs, called “Zero Waste,” is dedicated to reducing the amount of waste the city puts in its landfills. Their goals are to reduce San Francisco’s solid waste by at least 75% by 2010, and have nothing going to their landfills by 2020 (3). In order to achieve this goal the city passed the Mandatory Recycling and Composting Ordinance, which requires everyone in San Francisco to separate their waste into trash, recycling, and composting bins (3). The Ordinance took effect on October 21, 2009. Although the entire ordinance is revolutionary, the composting aspect of it is especially innovative and has been tremendously effective. According to Soko Made, a City Government Zero Waste Assistant, the city surpassed its goal for 2010 and currently reclaims around 77% of the waste it produces, primarily through recycling and composting. By the end of December 2009, approximately 75% of restaurants and 67% of houses had composting bins (1.1). The entire operation is run by Recology, a company that runs recycling and composting programs all across the Pacific Northwest (1.2).This is how it works:

Collection: In order to ensure the ordinance is as successful as possible, San Francisco has invested a lot of time and money in making composting extremely simple for its residents. As of October 21, 2009, residents were allowed to throw all food scraps, soiled paper, and plants in their green, 32-gallon, yard waste bins (1.1). In addition to this they received a 2-gallon "kitchen pail" to help them transfer food waste from the table to their green bin outside. If residents want the larger 64-gallon bin, however, or another kitchen pail, they can order them free of charge from Recology (1). All building owners, whether commercial or residential, are required to order bins for their buildings and as many kitchen pails (or acceptable replacement bins) as needed. They are also responsible for educating their tenants, employees, and contractors (including janitors) about what goes in each bin (3).Once residents have their bins they can put almost all of their pre- and post-consumer waste in it (1). (For a full list of what San Franciscans can and cannot compost, click here). The kitchen pails, which are meant to be kept by the sink or indoor garbage can, are a smart addition to the program because they combat residents’ potential laziness and make it just as convenient for them to compost their food scraps as it was to throw them away. Green bins are picked up weekly, on the same day as residents’ regular trash and recycling collection, but by a different truck (3).

Processing:After the compost material is emptied out of residents’ green bins it is driven 55 miles north to a compost facility in Vacaville, CA run by Jepson Prairie Organics, a subsidiary of Recology (4).There, food scraps and yard trimmings are mixed in an industrial sized grinder and put into JPO’s composting system, which monitors the mix's temperature and oxygen levels. This ensures that the compost contains the proper levels of nitrogen for decomposition (4). The composted material is then forced through a screen to remove large objects that will not compost quickly enough. When the compost comes out of the screen it gets placed in rows called “windrows” where it sits, decomposing. The windrows are turned and agitated every once in a while in order to keep oxygen in the piles and make sure all of the material is decomposing at the same speed. After a couple of weeks the compost is ready to be used as soil. The amount of time that the compost needs to fully decompose, with this process, depends on the weather, so temperature and oxygen levels are closely monitored in the windrows as well (4). The JPO facility processes approximately 11,000 tons of mixed organics, monthly, a large portion of that coming from San Francisco (4).

Distribution:Once the compost is bagged up it, goes to a couple of different places. A lot of local farmers and vineyard owners will buy the compost because of how good of a fertilizer it is. The compost goes to more than 75 local vineyards and farms, and is what many farmers claim helps them win awards for their wine and produce (1).The compost that is not sold to farmers is used in San Francisco’s parks and other wildlife areas in order to further benefit the community (1). The unseen benefits of this compost, however, are what really make this program a success. According to a Recology News Release, San Francisco has composted more than 620,000 tons of material since the program started, mostly comprised of food scraps (1.3). Since this waste was recycled and did not end up in a landfill, the city avoided creating 137,000 tons of methane gas and sequestered 18,400 metric tons of CO2 (1.3).